The variability of Indian summer monsoon rainfall (ISMR; both at interannual as well as intraseasonal timescales) has a direct impact on various sectors of public interest and economy such as agriculture, water resource, etc. So, the need of real-time extended range forecast system of the ISMR (monthly to seasonal scale) is not overstated. The present study is aimed at developing such a forecast system to predict rainfall (monthly and seasonal mean) one month in advance over 34 meteorological subdivisions of India for climate risk management in agriculture.

The northeast (NE) monsoon season (October, November and December) is the major period of rainfall activity over south peninsular India. This study is mainly focused on the prediction of northeast monsoon rainfall using lead-1 products (forecasts for the season issued in beginning of September) of seven general circulation models (GCMs). An examination of the performances of these GCMs during hindcast runs (1982–2008) indicates that these models are not able to simulate the observed interannual variability of rainfall.